Home > Medicare Facts > Medicare Has Set Enrollment Periods
Medicare Has Set Enrollment Peroids
The time in which you can enroll in one or more parts of Medicare is called an enrollment period.
Medicare has set enrollment periods each year as well as an initial enrollment period when you first become eligible and even special enrollment periods that may trigger due to certain life events.
These enrollment periods include:
Initial Enrollment
What:
- When you can first enroll in Original Part A and Part B.
When:
- A seven-month window that starts three months before the month you turn 65, includes your birthday month, and then ends three months after you turn 65.
During this time you can:
- Enroll in Medicare (Parts A and B).
- Enroll in a stand-alone Medicare prescription drug plan (Part D).
- Enroll in a Medicare Advantage plan (Part C).
Notes:
- If you sign up for Part A and/or Part B during the first 3 months of your Initial Enrollment Period, in most cases, your coverage begins the first day of your birthday month. However, if your birthday is on the first day of the month, your coverage starts the first day of the prior month.If you sign up the month you turn 65 or during the last 3 months of your Initial Enrollment Period, your coverage starts the first day of the month after you sign up.
- You have to enroll in Parts A and B unless you are automatically enrolled due to already receiving Social Security when you turn 65.
- You may incur late enrollment penalties for not signing up when you are first eligible.
- Some people with a disability, ESRD, or ALS may qualify for enrollment before their 65th birthday.
Medicare Supplement (Medigap) Open Enrollment Period
What:
- When Medigap (Medicare Supplement) is guaranteed issue.
When:
- A six-month window that starts the first day of the month you turn 65.
During this time you can:
- Enroll in a Medicare Supplement (Medigap) Plan.
Notes:
- You must enroll in at least Part B to buy a Medigap plan.
- Medicare Supplement (Medigap) is not guaranteed issue outside of this six-month initial window. That means you may not be able to enroll.
- Medicare Supplement (Medigap) prices generally increase as you get older, so even if you can enroll later you may not want to wait.
General Enrollment Period
What:
- When you can sign up for Part A and/or Part B if you didn’t sign up when you were first eligible and aren’t eligible for a Special Enrollment Period.
When:
- January 1 and March 31 each year.
Notes:
- You may still incur a late enrollment penalty if you wait to enroll during this time unless it occurs during your Initial Enrollment Period.
- When you enroll during general enrollment your coverage starts July 1st.
Annual Enrollment Period
What:
- In general, this is when you can make changes to your coverage and enroll in a Medicare plan.
- You can switch from Original Medicare to Medicare Advantage with or without a drug plan.
- You can switch from Medicare Advantage to Original Medicare.
- You can switch Medicare Advantage plans or without a drug plan.
- You can enroll in a Medicare Part D plan.
- You can drop a Medicare Part D plan.
When:
- October 15 to December 7 each year.
Notes:
- Coverage obtained during Annual Enrollment starts January 1st.
- Most plans automatically renew on January 1st if no action is taken.
Medicare Advantage Open Enrollment Period
What:
- You can make a one-time election to switch Advantage plans with or without a drug plan or to go back to Original Medicare if you are enrolled in Medicare Advantage.
When:
- January 1 and March 31 each year.
Notes:
- Coverage starts on the 1st of the following month after you make the change.
- If you got back to Original Medicare you can add a Medigap plan if you qualify for Medigap (check with your insurer).
Special Enrollment Period (SEP)
What:
- A Special Enrollment Period (SEP) is a period in which you can switch or drop Part C (Medicare Advantage) or Part D Drug plan outside of normal enrollment.
When:
Based on qualifying life events such as:
- You move out of your plan’s service area.
- You move back to the U.S. after living abroad.
- You move into or out of a skilled nursing facility, psychiatric facility, rehab hospital, or long-term care facility.
- Your employment or your employer-provided plan ends.
- Certain other events like natural disaster or an emergency, incarceration, employer or health plan error, or losing Medicaid coverage.
Notes:
- Not every qualifying event is listed above. Check Special Circumstances from Medicare.gov for more information.
- You can also use Special Enrollment to enroll in Part B under certain circumstances. See How to Apply for Medicare Part B During Your Special Enrollment Period (PDF).
Citation: Unpacking Medicare: What you need to know about Medicare enrollment periods (and when you can change your plan). AetnaMedicare.com.
Thomas DeMichele
Looking for Medicare Plans?
Use the button below to find Medicare Advantage and Medicare Drug Plans.
Already know what plan you are looking for? Try using the search bar.
More Facts on Medicare
Medicare Part D Coverage Phases
Starting in 2025 Medicare has four coverage phases for drugs, the Deductible Phase, the Initial Coverage Phase, and the Catastrophic Coverage Phase.
Your Drug Plan Can’t Charge More than $35 for a Month of Insulin
Since January 1, 2023, Part D plans can’t charge you more than $35 for a one-month supply of Part D-covered insulin. You also don’t have to pay a deductible for your insulin.
Some People Get Medicare Part A/B Automatically, but Many People Have to Sign Up
Most people are not automatically enrolled in Medicare Part A and Part B and have to sign up during their Initial Enrollment Period. The following are exceptions: If you’re already getting benefits from Social Security or the Railroad Retirement Board (RRB). If you’re under 65 and have a disability. If you have ALS (amyotrophic lateral sclerosis, also called Lou Gehrig’s disease). Meanwhile, Puerto Rico, has special rules for Medicare Enrollment.
Medicare Late Enrollment Penalties
Medicare Part A, Part B, and Part D all have late enrollment penalties for not signing up when you first become eligible. However, with Part A, penalties only apply to those who must pay a Part A premium. Please note each late enrollment penalty has its own rules.